Entomologia Experimentalis et Applicata (2001) 98, 225-239

G.S. Wheeler, F. Slansky Jr. and S.J. Yu (2001)
Food consumption, utilization and detoxification enzyme activity of larvae of three polyphagous noctuid moth species when fed the botanical insecticide rotenone
Entomologia Experimentalis et Applicata 98 (2), 225-239
Abstract: We assessed the effects of the isoflavonoid rotenone, an insecticidal allelochemical occurring in various legumes, on larval performance of three polyphagous noctuid species: the corn earworm (CEW), the fall armyworm (FAW) and the southern armyworm (SAW). As rotenone concentration was increased up to 1% fresh mass in an artificial diet, neither mortality (for all three species) nor food consumption (for SAW and FAW) was significantly affected, but developmental time of the latter two species was prolonged. In contrast, for CEW developmental time was shortened and food consumption declined, especially at the two highest rotenone concentrations. Final biomass of all three species declined as dietary rotenone increased.
Analysis of covariance (ANCOVA) was used to evaluate larval food utilization analogous to, but without the potential statistical problems of, the traditional ratio-based indices approximate digestibility (AD) and efficiency of conversion of digested food (ECD). Frass output, statistically adjusted to account for differences in consumption, increased with rotenone concentration for all three species, suggesting that, when ingested, this allelochemical interfered with the digestion and/or absorption of ingested food, especially at the higher concentrations tested.
Significant statistical interactions in the ANCOVA necessitated the use of utilization plots to examine the linear regressions between biomass gain and absorption at each rotenone concentration. At the two highest concentrations, rotenone tended to reduce the amount of food absorbed by the larvae, as well as their ability to convert the absorbed food to biomass.
When piperonyl butoxide, an inhibitor of the polysubstrate monooxygenase (PSMO) system known to metabolize rotenone, was added to the diet along with 0.5 or 1% rotenone, mortality increased significantly only for FAW, approaching or exceeding 50%. The only apparent effects of dietary rotenone on PSMO (aldrin epoxidase) activity (adjusted by ANCOVA for the covariate, crude homogenate protein) were for CEW, where activity decreased in all rotenone treatments compared to the control, and for SAW, where activity at the 3 lowest rotenone concentrations (0.001-0.1% fm) declined about 50% below that of larvae on the control diet, whereas at 0.5 and 1% rotenone, it increased approximately 2-fold over that on the control diet.
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Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Helicoverpa zea
	Spodoptera frugiperda
	Spodoptera eridania